1. Field of the Invention
The invention is directed to an improved fuel injection valve for internal combustion engines.
2. Description of the Prior Art
One fuel injection valve of the type with which this invention is concerned is known from German Patent Disclosure DE 199 01 057 A1, for instance, and has a valve body having a pressure chamber that can be filled with fuel under pressure. At a valve seat embodied in the pressure chamber, at least one injection conduit is embodied, which connects the pressure chamber with the combustion chamber of the engine. A valve needle disposed in the pressure chamber has a sealing face cooperating with the valve seat to open and close the opening of the injection conduit. If the fuel flows out of the pressure chamber to the injection conduit, the pressure in the pressure chamber is converted into kinetic energy by the small cross section of the injection conduit, resulting in a very fast fuel flow in the injection conduit, so that the fuel upon emerging into the combustion chamber is finely atomized, which contributes to good, clean combustion. The injection conduit is embodied in the form of a straight cylinder and has both a circular injection opening and a circular outlet opening. Because the cross section of the injection conduit is constant over the entire length, the conversion of the pressure into speed takes place solely at the injection opening of the injection conduit, so that relatively high flow losses occur there.
Conical injection conduits of a fuel injection valve are also known from European Patent Disclosure EP 0 352 926 B2, and in them the injection opening and outlet opening are circular, but the injection opening has a markedly larger diameter than the outlet opening. Preferably a plurality of injection conduits are distributed over the circumference of the fuel injection valve. However, these injection conduits have the disadvantage that if the injection opening increases in size, the web width between the injection openings must be reduced, which leads to a reduction in the stability of the valve seat and thus may cause material failure in this region because of the valve needle, which in the closing motion strikes the valve seat at high speed and thus exerts major forces on the valve seat.